Update:

This is no longer an issue as of 1.12.0, so the ticket can be closed.

Summary
In survival, the same 2 soundtracks keep playing over and over. It never plays any of the other soundtracks. This is much more noticeable if you edit the music_definitions.json file to make the music play without breaks. I don't know if this happens with the creative, end, and nether music as I haven't tested those yet. 

Steps to Reproduce

1. Download the vanilla resource pack template from the Minecraft wiki and find and open the music_definitions.json file and change the numbers in the "game" section to 0 for min_delay and 30 for max_delay.
2. Open the game and equip the resource pack
3. Enter a survival world and listen to the music.

Observed Results:

The game plays the same 2 survival soundtracks over and over and never the others.

Expected Results:

The game plays all survival soundtracks.